[TowerTalk] TowerTalk Digest, Vol 41, Issue 45

[CubexCo at aol.com]

In a message dated 5/18/2006 9:29:20 AM Eastern Daylight Time, 
towertalk-request at contesting.com writes:
Subject: Re: [TowerTalk] The simple Gamma Match?


> Now to the question: HOW DO YOU BUILD A GAMMA CAPACITOR OUT OF ALUMINUM 
> TUBING?
===========================================
Tom,
The simplest method and is pretty reliable is to use a combination of 
Aluminum tubing and coaxial cable.  Taking into account that typical RG 8 type cable 
is around 27mmf per foot, the procedure is to strip the outer jacket and 
shielding leaving the center conductor and dielectric.  Using the appropriate 
diameter aluminum tubing ( I think 3/8 or 7/16 works) slide the coax into the 
tubing.  I would liberally coat the cable with silicone grease to unify the 
dieletric and prevent moisture intrusion.  The depth of insertion determines the 
capacitance, also provides "tuning" the match.  Once the correct length is known, 
trim the calbe, seal the end and clamp the braid to your common point feed.   
Careful sealing will make it a reliable capacitor.  The silcone gease should 
prevent condensation build up.  For higher power use larger cable.

Norm W4QN